1. Field of the Invention
The present invention relates to nozzles for use on subterranean earth-boring rotary drill bits, earth-boring rotary drill bits equipped with such nozzles, and to methods for communicating drilling fluid to a face of an earth-boring rotary drill bit. More particularly, the present invention relates to nozzles exhibiting a converging diverging geometry and having a substantially bifurcated portion of a fluid passageway through the nozzles for directing drilling fluid to different locations on and around earth-boring rotary drill bits equipped with such nozzles.
2. State of the Art
Subterranean drilling operations generally employ a rotary drill bit that is rotated while being advanced through rock formations. Cutting elements or structures affixed to the rotary drill bit cut the rock while drilling fluid removes formation debris and carries it back to the surface. The drilling fluid is pumped from the surface through the drill string and out through one or more (usually a plurality of) nozzles located on the drill bit. The nozzles direct jets or streams of the drilling fluid to clean and cool cutting surfaces of the drill bit and for the aforementioned debris removal.
Because of the importance of the cooling and cleaning functions of the drilling fluid, others in the field have attempted to optimize these benefits by specifically orienting the nozzle exit to direct the drilling fluid to a predetermined location on a cutting surface of the bit. For example, U.S. Pat. No. 4,776,412 to Thompson describes a nozzle assembly designed to resist rotational forces while directing drilling fluid to a predetermined rotational position. The nozzle's internal chamber is preformed to direct the fluid at a specific angle. Likewise, in U.S. Pat. No. 4,794,995 to Matson, et al., a nozzle is disclosed that changes the direction of fluid flow by angling the exit of the nozzle chamber. Again, the angle of exit is predetermined and may only be rotated about its longitudinal axis. U.S. Pat. No. 4,533,005 to Morris is another example of an attempt to provide a nozzle that may be reoriented to provide fluid flow in a specific direction.
Other examples of nozzles for delivering drilling fluids include: U.S. Pat. No. 5,380,068 to Raghaven; U.S. Pat. Nos. 5,494,124, 5,632,349, and 5,653,298 to Dove et al., and U.S. Pat. No. 6,311,793 to Larsen et al. Further, U.S. Patent Application No. 2004/0155125 A1 to Kramer et al. discloses a nozzle having a somewhat oval opening. U.S. Patent Application No. 2004/0069540 A1 to Kriesels discloses high pressure fluid jet nozzles having, in one embodiment, a slotted opening.
The limited ability to control drilling fluid emanating from a nozzle in a desired fashion necessarily limits the potential efficiency of the cleaning and cooling functions of the drilling fluid. Further, since conventional nozzles direct flow of drilling fluid along a single direction or path at a relatively high velocity, impingement of the drilling fluid emanating from a conventional nozzle upon a portion of the drill bit (i.e., a blade or other portion of the body thereof) may cause excessive erosion or wear to occur. Particularly, in the case where a nozzle is designed for providing a single flow stream of drilling fluid toward multiple paths (e.g., two junk slots), excessive erosion and wear may occur on the leading end of the structure(s) (e.g., blade) separating the single flow stream into the multiple paths.
Thus, it would be advantageous to provide a nozzle for use in subterranean earth-boring drill bits which provides suitable cuttings removal impetus, but which reduces undesirable erosion of the drill bit within which the nozzle is installed during use. It would also be advantageous to provide a nozzle design that distributes the drilling fluid emanating therefrom more evenly than conventional nozzle designs.